Preparation of phosphinic chlorides by chlorination of phosphinothioic acids with elemental chlorine



PREPARATION OF PHOSPHINIC CHLORIDES BY CHLORINATION OF PHOSPHINOTHIOIC ACIDS WITH ELEMENTAL CHLORINE r Willis Craig, Willoughby, Ohio, assignor to The glfihnzol Corporation, Wickliife, Ohio, a corporation of t No Drawing: Application January 26, 1954,

Serial No. 406,330

6 Claims. or. 260-543 This invention relates to a novel method for preparation of acid chlorides. More particularly it relates to a novel method for containing acid chlorides. i o

Previous methods for preparing acid chlorides have generally involved the utilization of certain welhknown reagents, such asphosphorus pentachloride, phosphorus trichloride, thionyl chloride, etc. These reagents, while effective in most cases, are not as etficient as is sometimes desired simply because there is available from the reagent only one or two atoms of chlorine which will appear in the acid chloride product, whereas a relatively large proportion of the reagent molecule, such as sulful, phosphorus, chlorine, etc. is of no avail and constitutes an economic waste. Nevertheless, the use of these reagents is necessary when, as is generally the case, sim-,

pier and less expensive chlorinating reagents will not serve the purpose.

The phosphorus-containing acid chlorides which are produced in the process of this invention are illustrated by the structural formula:

Ar 01 wherein Ar and Ar are the same or different aromatic radicals, each bound to the phosphorus atom through a benzenoid carbon atom. Such compounds are the phosphinic chlorides. I v

. The availability of phosphinic chlorides in the past'has depended principally, upon. threepreparative methods. The one involved oxidation of a monochlorophosphine, usuallywith air under relatively mild conditions. A second method utilized a trichlorophosphorane as the starting material and this. was hydrolyzed in such a manner as to yield the corresponding" phosphinic chloride. The third method consisted in treating the phosphinic acid with either thionyl chloride or phosphorus pentachloride.

It is an object of the present invention to provide a process for the preparation of phosphinic chlorides. Another object is to provide such a process which is economical and convenient. Other objects will be apparent from the following description of the invention.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

Broadly stated, this invention relates to the method for preparing phosphinic chlorides having the formula:

Ar /0 a A! Cl wherein Ar and A1" are the same or different organic preparation of certain phosphorusradicals bound to phosphorus through a benzenoid carbon atom, which comprises reacting at least one diorgano phosphinothioic (thiophosphinic) acid in which the organo radicals are bound to phosphorus through a benzenoid carbon atom with chlorine.

The process is illustrated by the following equation:

wherein Ar and Ar arethe same or different aromatic radicals, each bound to the phosphorus atom through a benzenoid carbon atom. The aromatic radicals may be either substituted or unsubstituted hydrocarbon radicals, including aryl and alkaryl radicals, and are illustrated by the following specific examples: pheny'l, tolyl, xylyl, naphthyl, xenyl, chlorophenyl, dichlorophenyl, nitrophenyl, nitronaphthyl, anisyl, amylphenyl, waxphenyl, etc.

The process is particularly convenient and simple in its operation. Chlorine is introduced into the phosphinothioic acid at slightly elevated temperatures, preferably in the presence of an inert solvent. The solvent need only be inert to the action of chlorine under the conditions of the process and suitable solvents include principally the chlorinated hydrocarbons and aromatic hydrocarbons. The process is operable at room temperatures or lower, the reaction being somewhat exothermic, although it is preferred to utilize higher temperatures, up to and in some particular instances above C. Usuallythe temperature range of 20-80 C. is satisfactory.

The duration of the reaction is usually 1-3 hours. Reactions run at lower temperatures require, of course, a longer time than reactions run at higher temperatures and consequently, it is within the contemplated scope of this invention to carry out the process within the range of time of about 05-10 hours.

The aromatic phosphinic chlorides are in general liquids. The lower molecular weight members of this class are susceptible to distillation at diminished pressure and where purification of such a product is indicated, such purification is best accomplished by distillation.

The aromatic phosphinothioic acids which comprise the starting materials in the process of this invention are conveniently available via the alkaline hydrolysis of the corresponding aromatic phosphinothioic chlorides. These acid chlorides are in turn conveniently prepared by the reaction of phosphinodithioic acids with hydrogen chloride, as disclosed" in copending application Serial No. 406,326, filed January 26, 1954, and the preparation of the phosphinodithioic acids is effected, as indicated in copending application Serial No. 406,323, filed January 26, 1954, by the reaction of an aromatic compound with phosphorus pentasulfide in the presence of aluminum halide. The overall sequence of reactions involved in an ultimate synthesis of the phosphinic chlorides described herein is as follows:

4ArH P2S ZAmPSSH H28 2. AnPSSH HCl ArgPSCl H28 3. BH-

AI'zPSCl NaOH ArzPSOH NaOl 4. ArzPSOH C1: AlePOCl S=Cl,

The invention is illustrated in detail by the following examples.

Example 1 To a solution of 200 grams of diphenyl phosphinothioic acid in 250 grams of benzene there was introduced a stream of chlorine over a period of ninety minutes. The temperature rose from 28 C. to 72 C. before re ceding again to room temperature. Excess chlorine was removed by bubbling dry nitrogen through the mixture.

The mixture thenwas filtered and concentrated by heat- Example. 2

Percent S 0.9' P 1 1.5 Cl 1'4.6

Example 3 A. slurry of 406 gramsv of diphenyl phosphinothioic acid in 400 grams-of. benzene was treated with chlorine for two hours. Volatile materials were removed by distillation and the. residue was distilled to yield 360 grams of light yellow liquid, B. P. l90200 C./2 mm., which was substantially pure diphenyl phosphinic chloride. The analyses: were Percent S n. Trace Example 4 A slurry of 225 grams of diphenyl phosphinothioic acid in carbon tetrachloride was treated with a stream of chlorine until a clear solution resulted. This solution was concentrated by heating at reduced pressure (water aspirator); The'resid'ue was distilled to yield a: fraction boiling at l69-l80 C./0.8-2.3-mm. This fraction. was shown to be substantially pure diphenyl phosphinic chlorid 6.

Example Chlorine was bubbled into, a slurryv of 420 grams of di- (chlorphenyl)v phosphinothioic acid in. 400' grams of benzene for two hours. The temperature during. this time ranged from 50-70 C. The mixture was filtered and then concentrated by heating to a final temperature of 100 C./ mm. The residue was distill'edto yield a fraction boiling from 205-224 C./2 mm. The analyses of this fraction, substantially pure di-(chlorphenyl) phosphinic chloride; were as follows:

Percent The phosphinic acid. chlorides of thisinvention maybe employed as improving agents in lubricating; oils and greases, in asphalt emulsions, insecticidal compositions, as starting materials, for preparing, phosphorus. compounds, fireproofin'g' and stabilizing agents in' plasticizers and plastics, paint dryersfrust inhibiting compositions, pesticides;- foaming, compositions; cuttingoils-,meta'l drawing compositions, tanning assistants;.rnetal cleaning compositions, penetrating agents, gum solvent compositions, fat splitting agents, flotation agents, and improving agents for hydrocarbon fuels, etc.

Other modes of applying the principle of the invention may beemployed, change beihgmade as regards the details described, provided the features stated in' any ofthe following claims, or the equivalent of such, be employed. 1 therefore particularly point out and distinctly claim as my invention:

11 Themethod for preparing phosphinic chlorides having the formula:

Ar Gl' wherein Ar and Ar are non fun'ctional'. aromatic radicals bound to phosphorus through. a benzenoid carbon atom, which comprisesv reacting" a phosph'inothioic a'ci'd of'the following structure wherein Ar and Ar are non-functional aromatic radicals bound to phosphorus through a benzenoid carbon atom, with chlorine. j v

2. The method of claim lcharacterized further in that the aromatic radicals are aromatic hydrocarbon radicals.

3. The-method of claim 1 characterized further in that the aromatic radicals are chloro-aromatic radicals.

4'. The method of claim 1 characterized further in that the aromatic radicals are phenyl radicals.

5'. The. method of claim 1. characterized further in that the aromatic radicals are tolyl radicals.

6. The methodof claim 1 characterized further in that the aromatic radicals are chlorphenyl radicals.

No references citedi 

1. THE METHOD FOR PREPARING PHOSPHINIC CHLORIDES HAVING THE FORMULA: 